1. Field of the Invention
This invention relates to a recording and/or reproducing apparatus and more particularly to an apparatus using a disc-shaped record bearing medium.
2. Description of the Prior Art
Recording and/or reproducing apparatuses using, for example, a flexible magnetic disc as a record bearing medium are arranged to have the magnetic disc rotated by mounting the center core or hub thereof on a spindle or the like of a disc rotating motor. In this instance, if the engagement of the center core and the spindle is loose, the magnetic disc would not normally rotate. If, conversely, the engagement is too tight, the center core might be inadequately mounted on the spindle when the magnetic disc is loaded. To solve this problem, there has been proposed a magnetic coupling method in which a magnetizable piece such as an iron plate is secured to the center core and a magnet to the spindle so that the two can be magnetically coupled with each other. However, even with this magnetic coupling method employed, it is still difficult to ensure that the center core is correctly positioned on a reference plane such as a flange surface of the spindle when the center core is mounted on the spindle. It is thus difficult to keep the magnetic disc on a predetermined mounting plane which is arranged for positioning the magnetic disc relative to a signal recording and/or reproducing head. In the case of a still picture recording and/or reproducing apparatus which requires high precision in loading a record bearing medium, a force of several hundred grams is required for accurately mounting the center core on a spindle. In that case, therefore, use of a large magnet is mandatory. Then, the use of a large magnet comes to hinder efforts to reduce the size and weight of the apparatus.
This problem can be solved by arrangement to have the center core pushed by a pressing member in mounting the center core on the spindle in a manner as has been disclosed, for example, in U.S. patent application Ser. No. 591,383 filed Mar. 20, 1983, now abandoned.
Meanwhile, the apparatus of the above-stated kind is required to control and adjust the rotation phase of the magnetic disc to a predetermined phase in recording or reproducing a signal on or from the magnetic disc. To meet this requirement, at least one indicating member is provided on the center core of the disc for indicating the rotation phase of the disc while, on the side of the apparatus, a detecting member is arranged to detect this indicating member of the center core at a predetermined position and to produce a rotation phase signal. The apparatus of this kind is thus arranged to perform phase servo control over the disc rotating motor on the basis of the rotation phase signal thus obtained.
In cases where the rotation phase detecting member is thus provided in relation to the center core of the disc, the operating position of the detecting member is inevitably located very close to the operating position of the above-stated pressing member. This presents a problem as to how to prevent interference between the two members. Mechanical interference between them would damage or deform them or would hinder their operations to bring about an adverse effect on the recording or reproducing performance of the apparatus.